The scrotal circumference of a bull provides an important indication of his genetic merit for several important fertility traits. Increased scrotal circumference is associated with earlier age at puberty, increased semen production and improved semen quality. There is also evidence that increased scrotal circumference is associated with improved female fertility and earlier age at puberty in a bull’s daughters.

Interpreting Scrotal Size EBVs

Scrotal Size EBVs provide an estimate of the genetic differences between animals in scrotal circumference at 400 days of age. Scrotal Size EBVs are expressed in centimetres (cm).

Larger, more positive, Scrotal Size EBVs are generally more favourable. For example, a bull with a Scrotal Size EBV of +4 cm would be expected to produce sons with larger testicles at yearling age and daughters that reach puberty earlier than the progeny of a bull with a Scrotal Size EBV of -1 cm.

For more information regarding Scrotal Size EBVs, please contact staff at your BREEDPLAN processing centre.